Results of Kids' Brain Injury Hard to Predict

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Outcomes after pediatric brain injuries are highly variable, and estimating morbidity rates is particularly challenging for traumatic brain injury -- the most common form of acquired brain injury, a literature review found.

Note also that relatively good motor outcomes may obscure cognitive and behavioral problems.

Outcomes after brain injury in children remain difficult to predict and the evidence base is limited, posing challenges for families and clinicians about treatment decisions, a literature review concluded.

Children with major brain trauma and severe disability rarely survived in the past, but improvements in pediatric intensive care and a fuller understanding of trauma-related morbidity have led to a lowering of mortality, according to Rob Forsyth, PhD, of Newcastle University in Newcastle upon Tyne in England, and Fenella Kirkham, MD, of University College London.

Among the complex variables that influence post-injury morbidity are the type and severity of trauma, as well as patient and family characteristics, the researchers reported online in CMAJ.

With the goal of summarizing the available evidence on outcomes, Forsyth and Kirkham searched the published English-language literature, finding a major increase in recent decades in understanding of the pathophysiology of brain trauma.

Following the injury itself, a cascade of destructive events takes place involving inflammation, production of toxic free radicals, and alterations to the synaptic activities of neurotransmitters such as glutamate. These effects, in turn, can lead to apoptosis, and post-injury events have been considered a possible opportunity for intervention.

"However, optimism that neuroprotective interventions targeting a small number of shared pathophysiologies of secondary injuries would have widespread benefit has proven misplaced," the researchers observed.

Accordingly, clinicians continue to struggle as they provide counseling on treatment -- including possible cessation of care -- to families of brain-injured children.

An important factor that influences outcome following injury to the very young brain is a shift toward an earlier "neurochemical milieu," with increased plasticity that may restore synaptic networks but may not necessarily be helpful overall.

The nature of the injury also may play a role, with worse outcomes typically being seen with diffuse axonal injuries and with compromised perfusion pressure.

A further obstacle to predicting outcome is the inadequacy of assessment tools. Objective measures such as the Glasgow Outcome Score are overly simplified for use in young brain-injured children, who not only experience the short-term effects of trauma but also long-term neurologic and behavioral difficulties. Focusing simply on the restoration of motor function can lead to a lack of recognition of these longer-term outcomes, the researchers cautioned.

However, they noted that the literature had provided "relatively reassuring" data on recovery thresholds that may predict satisfactory recovery.

For instance, in one case-control study, children who were unconscious for no longer than an hour appeared to have no more behavioral sequelae than children with other injuries.

But another prospective study found that behavioral problems can persist even with less severe brain injuries, particularly if the traumas are repetitive.

Furthermore, the researchers wrote, "Late emotional and behavioral outcomes after traumatic brain injury are modulated by factors independent of the injury and its severity, particularly the social and family milieu to which the child returns."

Of particular concern was how the injury was inflicted, such as with shaking, where one study reported a 30% mortality among children admitted to the intensive care unit.

Other types of brain injury included near-drowning, which now has survival rates reaching 80% in children who rapidly return to consciousness, and infections such as meningitis. For meningitis and other encephalopathies, outcomes depend on factors including ischemia, intracranial hypertension, and white matter involvement.

The age of the child at the time of the brain trauma also may be influential, with some cerebral adaptations being possible in the very young, but the commonly held notion that recovery is more likely in earlier injuries is "naive," according to Forsyth and Kirkham.

"Early injury alters the entire developmental trajectory (the challenge of making 'a year's progress every year' with an injured brain), and effects can compound through childhood," they observed.

Improved evaluations at the time of injury, such as through the use of neurophysiologic biomarkers, EEG monitoring, and evoked potentials, may in the future aid in assessing the likely trajectory following injury, particularly when used in the context of clinical data.

The authors concluded that the limitations of current neuroprotective efforts following brain injury heighten the importance of primary prevention of trauma, along with close attention to the psychological, behavioral, and educational needs as the children develop.

Funding for the study was not disclosed.

The authors reported no competing interests.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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